1. Field of the Invention
This invention lies in the field of medical surgery performed on patients. It involves the important capability of determining the total blood loss from the patient during a surgical operation. More particularly it involves an instrument which can respond to the increasing weight of a container into which blood is pumped from a cavity in a patient. It also involves the weighing of surgical sponges, so that the total blood content of the sponges as they are placed in a container on a weighing machine can be determined, by determining what part of an increase in weight is blood and what part is added tare.
2. Description of the Prior Art
In the prior art various means have been described for measuring the total blood loss for a patient. One is to weigh the total blood extracted by a vacuum pump from a body cavity; another way is to estimate the weight of blood on each sponge, and to sum this number for each of the known number of sponges. There are other chemical methods of determining the amount of blood in the sponges for example, but have possible errors due to the possible presence of other electrolytes in the blood, and so on.
There is also another important factor which is not taken into account by any of the prior art known to me. This is the fact that there is a very considerable evaporation of blood during the operation from the containers that hold the waste blood. As a general operating practice the operating room is quite cool, and of course the blood is at body temperature, and the amount of blood loss by evaporation can be quite considerable.